PARIS — French Finance Minister Michel Sapin on Friday vigorously denied an allegation that he had made an off-color joke and snapped the elastic of a female journalist’s underwear while she was bending over — an accusation that prompted calls from a feminist group for him to step down.

In excerpts from a book titled “L’Elysée, off,” journalists identified the “occupant of Bercy” shorthand for the finance ministry — as meaning that Sapin had made the gesture, which had first been described in an open letter denouncing macho behavior by politicians and signed by 40 female journalists.

The authors of that letter, which was published last year in the left-leaning Libération daily, did not identify who was behind the gesture or the comment (“Ah, what is this that you’re showing me?”).

But, while both Sapin and Economy Minister Emmanuel Macron work out of the Bercy finance ministry, the former is more traditionally associated with the location and has worked there for longer.

Le Parisien newspaper quoted several anonymous sources as saying that an off-color incident had indeed taken place, but not as described by the book’s authors.

Sapin’s spokeswoman issued a strongly worded denial of the incident on Twitter.

“Michel Sapin categorically denies the false and libelous allegations made in a book published over the last few days,” Helene Fontanaud wrote in a tweet.

According to Europe 1’s website, authors of the book said Sapin’s entourage had previously “attempted to justify” the gesture as a “schoolboy prank” and that the person in question had taken it the wrong way.